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Interaction of unequal anti-parallel vortex tubes

Marshall, Jeffrey S. and Brancher, Pierre and Giovannini, André Interaction of unequal anti-parallel vortex tubes. (2001) Journal of Fluid Mechanics, 446. 229-252. ISSN 0022-1120

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Abstract

A computational study is reported of the close interaction of nominally anti-parallel vortex tubes with unequal strengths. The computations are performed using a spectral method, with periodic boundary conditions and vortex Reynolds number Re=1500. The vortices are perturbed by a wavelength for which the pair is unstable because of their mutual interaction. The numerical method is tested for the case of equal-strength vortices, which exhibits the classic vortex reconnection phenomenon typifed by bridging between the vortex cores and formation of thin vorticity threads as the bridged sections advect away under their self-induced velocity. Computations for vortices of unequal strengths are reported for cases with small, moderate and large strength differences. The bridges between the vortex structures form loops that twist owing to the unequal vortex strengths. In the thread region, the vortex interaction is controlled by competition between the effects of stretching of the weak vortex as it wraps around the stronger vortex and the core distortion induced on each vortex owing to the straining imposed by the opposing vortex. For cases with large vortex strength difference, the strong vortex remains nearly straight as the weak vortex wraps around it, inducing an interlaced pattern of positive and negative vorticity spirals within the core of the strong vortex. Over long time, the bridge regions form loops that propagate away from the thread region for cases with small strength difference and wrap around the nearly columnar strong vortex for cases with large strength difference.

Item Type:Article
Additional Information:Thanks to Cambridge University Press. The original PDF of the article can be found at : https://www.cambridge.org/core/journals/journal-of-fluid-mechanics/article/interaction-of-unequal-anti-parallel-vortex-tubes/5D824E2C7B2D9F560F0B79AC1081C585
HAL Id:hal-01739432
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UT3 (FRANCE)
Other partners > Iowa State University - ISU (USA)
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Deposited On:21 Mar 2018 07:20

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